globals, UIFont and UILabel extensions

// Some of the things I use in my projects
import UIKit

let sharedApp = UIApplication.shared
let noteCenter = NotificationCenter.default
let userDefaults = UserDefaults.standard

func assertOnMain()   { assert(Thread.isMainThread) }
func assertOffMain()  { assert(!Thread.isMainThread) }
func assertFail()     { assert(false) }

struct ScreenSize {
  static let width = UIScreen.main.bounds.size.width
  static let height = UIScreen.main.bounds.size.height
  static let maxLength = max(ScreenSize.width, ScreenSize.height)
  static let minLength = min(ScreenSize.width, ScreenSize.height)
}

struct DeviceType {
  static let iPhone4orLess = UIDevice.current.userInterfaceIdiom == .phone && ScreenSize.maxLength < 568.0
  static let iPhone5 = UIDevice.current.userInterfaceIdiom == .phone && ScreenSize.maxLength == 568.0
  static let iPhone6 = UIDevice.current.userInterfaceIdiom == .phone && ScreenSize.maxLength == 667.0
  static let iPhone6p = UIDevice.current.userInterfaceIdiom == .phone && ScreenSize.maxLength == 736.0
}

extension UIFont {
  class func slim(fontSize: CGFloat) -> UIFont {
    return UIFont(name: "Avenir-Roman", size: fontSize)!
  }
  
  class func bold(fontSize: CGFloat) -> UIFont {
    return UIFont(name: "Avenir-Black", size: fontSize)!
  }
}

extension UILabel {
  convenience init (frame: CGRect, text: String, textColor: UIColor, font: UIFont, alignment: NSTextAlignment, spacing: Bool) {
    self.init()
    self.frame = frame
    self.text = text
    self.textColor = textColor
    self.font = font
    self.textAlignment = alignment
    if spacing {
      self.setTextSpacing(spacing: 1.15)
    }
  }
  
  func setTextSpacing(spacing: CGFloat){ // http://stackoverflow.com/a/36822550/611879
    let attributedString = NSMutableAttributedString(string: text!)
    if textAlignment == .center || textAlignment == .right {
      attributedString.addAttribute(NSKernAttributeName, value: spacing, range: NSRange(location: 0, length: attributedString.length-1))
    } else {
      attributedString.addAttribute(NSKernAttributeName, value: spacing, range: NSRange(location: 0, length: attributedString.length))
    }
    attributedText = attributedString
  }
  
  func setText(string: String!, alignment: NSTextAlignment, spacing: CGFloat){
    if string != nil && string.characters.count > 1 {
      text = string
      textAlignment = alignment
      setTextSpacing(spacing: spacing)
    }
  }

  static func navTitleLabel(text: String) -> UILabel {
    let titleLabel = UILabel(frame: CGRect(x: 50, y: 0, width: ScreenSize.width-100, height: 13))
    titleLabel.text = text
    titleLabel.textColor = UIColor.white
    titleLabel.font = UIFont.bold(fontSize: 15)
    titleLabel.setTextSpacing(spacing: 1.15)
    titleLabel.sizeToFit()
    return titleLabel
  }
}